Coordinate measuring machines (CMMs) are used to measure component parts. Different sensor systems are used depending on the particular application. Together with a measurement head, e.g., with a measurement head of the VAST® family from Zeiss, a sensor system forms a measurement head system. A sensor system can be based on tactile or optical sensors and can operate by contact or contactlessly. As an example of a tactile, contact-based sensor system, stylus configurations are used for example. These stylus configurations can be actively changed during a measuring process. The stylus configurations are kept in a special magazine location.
The various stylus configurations are coupled to the measurement head by a change-over interface, which is standardized. Each probe sphere present on the stylus configuration must be calibrated once. After the calibration, the stylus configuration can be changed as often as desired, without renewed calibration.
In the case of large and complicated workpieces, for example an engine block and a cylinder head, with many features to be measured, many stylus configurations are needed for the complete measurement. A stylus configuration has, for example, a plurality of probes (having a shaft and, for example, a probe sphere) which are oriented in different directions. The space required for storing various stylus configurations is often a limiting factor, besides the costs. In the measurement of complicated workpieces, there are features that must be measured with a high degree of precision and some that must be measured with less precision.
For the features that must be measured with less precision, it is generally possible to use rotating/pivoting measurement head systems, e.g., a lockable rotating/pivoting unit RDS® from Zeiss, which allows the stylus to rotate about two axes in discrete 2.5° steps. The number of stylus configurations needed can thus be greatly reduced. A disadvantage is that such systems provide less precision. For example, this precision is often not sufficient when measuring an engine block and a cylinder head. Moreover, if small inclined bores with a certain depth must be measured, the discrete steps in the angle adjustment are problematic. This then leads to undefined probing in the bores and, consequently, to an incorrect measurement.